1. Field of the Invention
The present invention relates to a tank for waste ink not contributing to the image recording and relates to an ink jet recording apparatus.
2. Description of the Related Art
The ink jet recording method has been widely used for a printing apparatus or a copying apparatus because it is low in noise and inexpensive in running cost as well as the apparatus can be easily minimized in size and adapted for a color system.
There is an ink jet recording apparatus having a pump for compulsively ejecting ink from a plurality of ink ejection orifices of a recording head. Such a pump is made to operate when the orifice is clogged with ink which is thickened and solidified in the orifice due to the evaporation and/or dry to cause the deflection (from the target direction) or the interruption of the ink jet, or when foreign matters adhere to the orifice to result in the erroneous ink jet, or when bubbles dwell in an ink feeding path from an ink tank to the orifice of the recording head, so that the thickened and solidified ink, the foreign matters or the bubbles are compulsively discharged from the orifice by the action of the pump to recover the ink head to the normal ink jet operation. In general, the ink jet apparatus with a mechanism using such a pump for compulsively discharging the ink from the orifice has a waste ink storage for storing the waste ink thus discharged.
There has been a waste ink storage in the prior art wherein a waste ink absorber is accommodated therein for absorbing and retaining the ink so that the waste ink discharged from the pump is absorbed in the waste ink absorber. According to this waste ink storage, the waste ink absorber is not accommodated within a sealed container but vents or the like are provided to facilitate the evaporation and dry of the waste ink so that as much the ink as possible could be absorbed in the waste ink absorber. The waste ink storage of this type is required to quickly absorb the ink in the waste ink absorber as well as to prevent the waste ink once absorbed therein from leaking from the waste ink absorber. Also, to effectively use the waste ink absorber, it is necessary for the ink to be absorbed throughout the waste ink absorber.
For the purpose of satisfying such demands, a waste ink storage has been proposed wherein a combination of a waste ink absorber having a high ink absorbing rate with that having a high ink retaining capacity is used, or a waste ink absorber with a density gradient so that the farther the distance from a waste ink inlet position, the higher the density thereof is used (see Japanese Patent Application Laid-open No. 6-198913 (1994)). Alternatively, a waste ink storage has been proposed wherein grooves are provided in the inner wall of an ink tank brought into contact with an ink absorber (see Japanese Patent Application Laid-open No. 8-112914 (1996)).
Recently, the resistance to water or the resistance to light of the recorded image obtained by the ink jet recording system is also required, and the improvement of ink has been done for this purpose. For example, various inks have been used, such as one which becomes insoluble to water after dried or one using pigment as a colorant. Some of these inks become considerably viscous to lose the fluidity (for example, due to the gelation) when evaporated and dried.
The prior art waste ink absorber has the following problems when such inks are absorbed therein:
That is, in the ink jet recording apparatus, the ink is not frequently discharged from the orifices of the printing head by the pump and the waste ink is absorbed in the waste ink absorber at a very low rate while requiring a long time period. In such a case, the waste ink tends to evaporate to be highly viscous and lose the fluidity in the vicinity of the inlet position of the waste ink absorber, resulting in the clogging of the waste ink absorber.
Therefore, even if the waste ink absorber has a capacity capable of absorbing all the waste ink possibly generating during the product life of the recording apparatus, there might be a problem in that the waste ink overflows from the waste ink storage before the waste ink has diffused to the entirety of waste ink absorber if a portion of the waste ink absorber loses the absorbency in the vicinity of the waste ink inlet position. According to Japanese Patent Application Laid-open No. 8-112914 (1996), for instance, a distance between grooves provided in the inner wall of an ink tank and the waste ink absorber is narrow. This causes a problem that clogging of the waste ink absorber easily occurs due to the waste ink, thereby failing to achieve required product life in some case.
The present invention has been made to solve the above-mentioned technical problems in the prior art, and an object thereof is to provide a waste ink tank and an ink jet recording apparatus capable of avoiding the leakage of waste ink from a waste ink storage by the improvement in the waste ink absorbing performance thereof through a simple and inexpensive constitution.
A waste ink tank according to the present invention for introducing waste ink not contributing to the image recording thereinto and absorbing/retaining the waste ink in a waste ink absorber is characterized in that a recess is formed in the waste ink absorber and extends to include an inlet position for the waste ink.
An ink jet recording apparatus according to the present invention for recording an image on a recording medium by using an ink jet recording head from which ink droplets are ejectable is characterized in that the apparatus comprises a waste ink tank having a recess and a recovery means for discharging ink not contributing to the image recording from the ink jet recording head as waste ink.
As described above, according to the present invention, since the recess in a slit form or others is provided in the waste ink absorber to introduce waste ink thereinto, it is possible for the ink to diffuse via the recess even if the waste ink absorber partially loses its absorbency due to viscous ink, and consequently for the entirety of the waste ink absorber to be effectively used. Thus, the waste ink absorbency is improved by an extremely simple and inexpensive constitution.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.